Due to the continuous expansions in the IC and LCD production capacities, in which 30% or more of the water consumption is from cleaning, the amount of the organic wastewater increases in multiples. Further, the Science Parks in Taiwan demand a newly built semiconductor process to have a water recovery ratio (recycling from the discharged Water to the ultra-pure water system and other secondary water use system) of more than 85%. The required water recovery ratio for an existing plant is 75%. Therefore, the advocacy of recovery and reuse for the process water is of great urgency.
The applicant of the present application discloses a process and a system for processing wastewater containing organic compounds in US patent publication No. US2003-0106855A1. The system includes a UV/ozone oxidation removal module, or one or more removal modules connected in series whereas such a serial connection can be continuous or discontinuous. A UV/ozone oxidation removal module mainly includes an ozone generator, an ozone injector, an ozone dissolution tank, a gas-liquid separator, an ozone destruct unit, a UV reaction tank, and a recycling pipeline. The efficiency of this UV/ozone oxidation removal module is good in treating the wastewater containing no foaming substance. A suitable gas-liquid separator for use in this US patent publication includes a centrifugal type degassing separator, for example the GDM™ degassing separator, available from GDT Water Process Corporation (U.S. Pat. No. 5,674,321). The GDM™ degassing separator has a tank of 316L stainless steel, and a centrifugal device mounted in the tank for destroying foams into liquid and gas, thereby the resulting liquid exits from the bottom of the tank and the resulting gas rises to the ozone destruct unit on the top of the tank. However, the cleaning procedures adopted by the photoelectric industries use surfactants, detergents or like organic chemicals, so that the effluent comprising foams, moisture, ozone or other gases is cannot be separated sufficiently in the degassing separator, which exits from a constant pressure valve connected to the top of said ozone dissolution tank. Consequently, a portion of the foams prevails and flows into the ozone destruct unit, causing the ozone destruct unit flooding, and thus the operation of UV/ozone oxidation removal module will have to be stopped. Therefore, the function of the UV/ozone oxidation removal module cannot be fully achieved when a foaming wastewater containing organic contaminants is to be treated.